Watertight watchcase



March 18, 1952 E. vAuRlLLoN WATERTIGHT WATCHCASE Filedn March 27, 1945 Patented Mar. 18, 1952 WATERTIGHT WATCHCASE Emile Vaurillon, Geneva, Switzerland Application March 27, 1945, Serial No. 585,075 In Switzerland May 2, 1944 2 Claims.

The present invention relates to new and useful improvements in round water-tight watch cases opening on the back and in which the glass or crystal in the shape of a cap, is provided with a rim which forms a shoulder and encloses the movement and allows for the direct tight junction between said glass and the case back.

Although it opens on the back, the case has thus but one single water-tight joint, apart obviously from those necessitated by the outside controlling parts. If the cup-shaped crystal is made of a material capable of considerable elastic deformation, such as Plexiglas, it is possible to ensure the water-tightness of the joint without the interposition of any packing,

There are already in existence cases designed on this principle, in which assembling is effected by forcing the back inside or outside the rim of the cup-shaped crystal. The radial pressure produced by the insertion is sufficient to ensure the Water-tightness. This device necessitates certain precautions in its manufacture. It requires, for surety, perfectly smooth machined or even polished contacting surfaces, in particular those of the metallic part. In fact, if this condition is not fulfilled, when said metal part is forced inside or onto the rim of the crystal, it will act on the case like a file and make grooves parallel to the axis of the case through which liquid or gas may infiltrate.

The present invention has as an object the elimination of this drawback.

It consists of a water-tight watch case including a cup-shaped crystal made of flexible material, the rim of which, surrounds the movement and is secured to the case back so as to be watertight.

The feature of the invention is that the inside surface of the crystal rim is pressed against the corresponding external surface of the bottom rim by a metal ring forced outside the crystal rim.

Figs. 1 through 5 of the drawing show, by way of example, five forms of the'invention, all in partial section taken on a line through the axis of the case. The cases are always round ones.

The case of the first form of invention, Figure 1, includes the flexible cup shaped crystal I, the back 2 and the casing 3 fitted with the usual strap or bracelet brackets. The rim 4 of the back, the outside surface of which is cylindrical, ts freely into the end 5 of the cap rim, which has also a cylindrical shape. This end 5 constitutes the shoulder of the watch case. When the back is placed in its position, the metallic ring 6, the inside of which is so machined as to be smaller than that of the outside Wall of the rim end 5 is pressed onto said end. The elastic deformation of the ring due to its being forced creates a radial pressure which presses the end 5 of the crystal rim against the rim part 4 of the back, thereby ensuring the water-tightness of the assembly. A shallow flange l is provided on the periphery of the back in order to cover, with an aesthetic purpose, the edge of the crystal rim. Some nailgrooves 8 and 9 provided on the whole or on a part of the circumference facilitate the dismantling.

The form of invention of Figure 2 differs from the above in the fact that the contacting surfaces of the end 5 and of the ring 6 are slightly tapered. This facilitates the insertion of the rim in the ring and decreases the effort of dismantling.

In the form of invention of Figure 3, the contacting surfaces of the rims 4 and 5 are also slightly tapered in order to ensure a greater sta.- bility of fastening between the crystal I and the back 2.

In the form of invention of Figure 4, it is an inside shallow flange l0 of the ring 6 which covers the edge of the end 5 of the crystal l.

The end of the casing 3 of the form of invention of Figure 5 ts into a tapered notch Ilof the ring 6.

In all forms of invention, the sizes of the ring 5 and the material of which it is made must be such that the radial pressure exerted when the yielding point is reached is suflicient to ensure the water-tightness. If, at this moment, the pressure still permits an easy assembling and dismantling, the automatic setting thereby created allows for a broadening of the manufacturing gauge limits.

The watch case in accordance with the invention, opening on the back makes it possible, after having removed the back, to reach directly the setting-lever screw of the movement and to free the winding stem. It therefore avoids the use of special devices such, for example, as a divided winding stem.

What I claim as my invention and desire to secure by Letters Patent of the United States is:

l. A water-tight watch case comprising a cup shaped crystal of exible material having a deep integral rim for surrounding a watch movement, a metal back having a shallow rim freely received within the rim of said crystal, and a metal ring surrounding and forcibly pressing the crystal rim about the rim of the back, said metal ring having an inwardly extending edge flange concealing the free edge of the crystal rim.

2. A water-tight watch case comprising a cup shaped crystal of exible material having a deep integral rim for surrounding a watch movement, a casing surrounding said rim and having an inturned flange engaging the edge of the face of said crystal, the free edge of said rim being of increased internal and reduced external diameter to provide a relatively thin axially extending flange, a metal back closure having a short rim freely received within the open end of said axially extending flange, and a metal ring surrounding the 10 outside of said ange for compressing the same about the periphery of said back closure, and said easing having a free edge overlying a portion of said metal ring.

EMILE VAURILLON.

REFERENCES CITED The -following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,302,340 Morf Nov. 17, 1942 FOREIGN PATENT-,S Number Country Date 195,115 Switzerland Apr. 1, 1938 196,014 Switzerland May 16, 1938 211,335 Switzerland Dec. 2, 1940 

